Preparation of a Novel Double-Skinned Forward Osmosis Membrane by Reserve Draw Solute in Support Layer

Forward osmosis (FO) is an emerging membrane separation technology, which has attracted wide attention in recent years. However, the performance of this technology is seriously restricted by internal concentration polarization (ICP) and fouling propensity. In this work, we reported a double-skinned forward osmosis membrane that fabricated on hydrophilic nylon microfiltration support though interfacial polymerization to enhance the performance and anti-fouling property. In order to study the effect of reverse draw permeability in the double-skinned membrane,draw solute was reserved in the support layer to simulate solute diffuse into the support layer from the draw solution. The structure and performance of the forward osmosis membrane were studied by fourier transform infrared spectroscopy, water conduct angle, scanning electron microscopy and forward osmosis experiment. The result showed that the retention of solute concentration has effect on the water flux of the double-skinned FO membrane. The reserved solutes changed the effective driving force between active layer, that improved the water flux. When the concentration of the reserved solute was close to the draw solution, the water flux of double-skinned FO membrane which immersed into 0.45M NaCl solution was enhanced 14.58% compared to the double-skinned FO membrane without NaCl solution immersion process. Moreover, the double-skinned FO membrane exhibits a good anti-fouling property during a long-term forward osmosis operation. This research offers a promising approach to study the relationship between reverse solute diffusion and ICP in double-skinned FO membrane. And it also provides a new idea to enhance the performance of double-skinned FO membrane.